Actually, it is a positive (self-accelerating) feedback loop--and there are dozens of them, all accelerating global warming. worldwide. Remember, "positive" and "negative" have precise meanings in mathematics that can often be the polar opposite of the moral connotations these vague terms have acquired outside of mathematics. In cybernetics, "positive" feedback is normally catastrophic, while "negative" feedback is essential for self-regulation (like higher temperatures switching off power in a thermostat).